Inverted dispensing pumps are commonly used to dispense any number of liquids, such as liquid soap and the like. Typically, they involve some housing or mounting on which a container is mounted upside down, with a mouth of the container communicating with the intake of a dispenser pump. One issue with inverted dispensing pumps is the complete evacuation of fluid from the container. When the container is inverted, the pump is likewise inverted with its intake extending far inside the container. This causes a fluid to remain within the neck of the container, which in turn is wasted. One unique solution to tackle this container evacuation issue has been to draw the fluid with a cap received over the intake such that the opening of the cap draws fluid from closer to the neck of the container. An example of this in a unique solution has been described in U.S. Pat. No. 7,461,762, which is hereby incorporated by reference in its entirety. While this design provides a significant improvement, there are still a number of issues that need to be addressed.
For instance, the amount of fluid drawn into the pump during a given stroke can be somewhat restricted depending on the construction of the valve system. The valve needs to rapidly open and close in order to facilitate efficient pumping of the fluid, while at the same time, the valve needs to open wide enough to allow a sufficient amount of fluid to be drawn. Moreover, the valve system can be difficult to retrofit for both inverted and non-inverted pumping applications. Due to gravity, conventional valve systems, such as ball valves, may not be able to be properly seat when the pump is inverted. Umbrella valves may experience similar difficulties. Thus, there needs to be improvement in this field.